Choline salicylate is a well known analgesic compound having desirable pharmacological and therapeutic properties, as described in U.S. pat. No. 3,069,321. The compound, however, possesses an inherent limitation of being highly hygroscopic so that it is not possible to prepare pharmaceutically acceptable, solid dosage forms which are useful for oral administration in the course of choline salicylate therapy of humans and animals. Although crystalline choline salicylate, melting at about 50.degree. C., is known, its hydroscopic properties are such that trace amounts of moisture are sufficient to reduce the crystalline compound to the liquid state and no matter how stringent the effort to remove the absorbed moisture, the product remains in liquid state so that it cannot be used in forming stable solid dosage forms for pharmaceutical use.
Much effort has been made to prepare solid pharmaceutical dosage forms of choline salicylate. Thus, U.S. Pat. No. 3,297,529 provides mixtures of choline salicylate and magnesium sulfate to produce a solid product. U.S. Pat. No. 3,326,760 relates to the formation of an absorbate with polygalacturonic acid. U.S. Pat. No. 3,759,980 relates to the formation of a chemical compound of choline salicylate and magnesium salicylate, which is a solid. However, none of the methods described as solving the problem of providing choline salicylate in stable, solid, unit dosage-forms as described above, have as yet proved to be pharmaceutically satisfactory. A solid unit dosage form to provide a therapeutically sufficient quantity of choline salicylate for the required therapeutic purposes and also remain stable over sufficiently long periods of time to permit marketing of the same, has not been made commercially available, as yet.